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fancompute / legume

🌱 Guided-mode expansion of photonic crystal slabs
https://legume.readthedocs.io/
MIT License
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Is posible to add a mirror/boundary condition on one side? #54

Open jbuencuerpo opened 1 year ago

jbuencuerpo commented 1 year ago

Hello, I have checked the examples, but I am wondering if it is possible to calculate the bands for a structure with a bottom mirror. For example a slab with a pattern with air above and below, but as boundary condition or adding an additional layer with a the bottom a mirror. Something like this,

Open/Air/Slab/Air/Mirror

Thank you,

momchilmm commented 1 year ago

It is not directly possible. Actually it would be a nice project if someone had the time for legume projects... :) There's probably an analytic expression for the modes of the system with a mirror, and once you have the correct basis, everything else should just work!

There is actually a work-around too. The mirror can be replaced by just literally mirroring the system, and the difference between PEC/PMC is just the difference in which of the sigma_xy reflection modes you incorporate. I know that this works very well for a slab that's sitting directly on a mirror. That is to say if you have something like air -> slab of thickness d -> mirror, you can simulate this by just doing air -> slab of thickness 2d -> air. In your case, you can try something like air -> slab -> air x 2 -> slab -> air. However, one potential problem I anticipate is finding the basis modes of the two very weakly coupled, identical slabs. The modes will be very close to degenerate and I'm not sure if legume will handle this well (but if the air between them is not very thick, it might). I remember a long time ago someone having some issues with that but give it a try and let me know!

jbuencuerpo commented 1 year ago

Ok, thanks I will try using that approach. I have problems where the air/dielectric between both are not very thick so it may work. Thanks again.